FRANKFORT — A government watchdog group is raising questions about a politically popular proposal that would allow overseas military members to cast ballots via email.

Common Cause of Kentucky argues that votes submitted over the Internet are vulnerable to hackers.

Richard Beliles, chairman of Common Cause of Kentucky, sent letters outlining his concerns Wednesday to Secretary of State Alison Lundergan Grimes and Senate and House leaders. He attached news stories and research from federal agencies and computer scientists warning about the perils of online voting.

"We strongly recommend against allowing ballots to be cast online via email, e-fax or through Internet portals," the letter said. "Online voting presents a direct threat to the integrity of elections in Kentucky because it is not sufficiently secure against fraud or malfunction."

Republican Senate leaders have said making it easier for military members to vote is their top priority, promising to make it Senate Bill 1 when the proposal is drafted and filed. House Democrats have also spoken favorably of the initiative, which Grimes announced in September.

A spokeswoman for Senate President Robert Stivers, R-Manchester, said that Stivers will consider the security concerns raised by Beliles. "Senate Bill 1 is still being drafted," said Lourdes Baez-Schrader, a spokeswoman for Stivers . "Senator Stivers takes the security concerns seriously and wants to make sure the bill offers sufficient protections."

Lynn Zellen, a spokeswoman for Grimes, said Grimes has never backed Internet voting, only allowing overseas voters to return ballots via an email attachment. "But any eventual law and administrative regulations promulgated thereto will ensure the security and integrity of the voting process," Zellen said.

The Pentagon's Federal Voting Assistance Program reports that 24 states allow for the electronic return of ballots, either via an Internet portal or email. Those 24 states have had no reported problems with their electronic voting, Zellen said.

Still, the National Institute of Standards and Technology, a federal agency that works with industry, issued a statement in 2012 that cautioned against voting via the Internet, including email, because of security concerns. In 2010, a group of University of Michigan computer scientists were able to penetrate an Internet voting system for overseas voters. The scientists were able to change people's votes and directed the system to play the University of Michigan's fight song.

Currently, Kentucky mails absentee ballots to soldiers, but it sometimes takes too long for them to be delivered and returned, particularly if a soldier is in a war zone.

In Kentucky's 2012 general election, 1,747 overseas ballots were issued, 1,397 were returned and 61 were rejected because they were received after 6 p.m. on election day, according to Grimes' office.

Beliles said a better way to get overseas ballots into the hands of military personnel would be to send them via email and allow voters to return them via regular mail.